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Friday, October 02, 2009

What is ultimately possible in physics?

Thanks to my jetlag I woke up hours before sunrise, and used the early morning hours to finish my FQXi essay. This years' topic is "What's ultimately possible in physics?" You find the list with submissions here, the deadline is midnight today. I haven't yet had time to look at any of the other essays, but I'll check these out when I'm back from the conference. It promises to be an interesting contest.

I had pushed the question the contest raised back and forth for a while, and finally came to the conclusion that it cannot be answered. My essay explains the line of thought that lead me to this conclusion. You find my submission on this website, title and abstract below.

At the Frontier of Knowledge

At any time, there are areas of science where we are standing at the frontier of knowledge, and can wonder whether we have reached a fundamental limit to human understanding. What is ultimately possible in physics? I will argue here that it is ultimately impossible to answer this question. For this, I will first distinguish three different reasons why the possibility of progress is doubted and offer examples for these cases. Based on this, one can then identify three reasons for why progress might indeed be impossible, and finally conclude that it is impossible to decide which case we are facing.

45 comments:

Bee, Thanks for the interesting read, I thought it was very good treatment of the question.

One thing kind of bothered me:

“Shut up and calculate” is a still prevalent pragmatic approach frequently complemented by the attitude that there is nothing more to understand than what our present theories describe, and all questioning of the foundations of quantum mechanics is eventually nothing but a waste of time, or a pastime for philosophers, or maybe both amounts to the same.

Is the "shut up and calculate" view actually correlated with that kind of pessimism? Certainly none of the three people to whom the phrase is commonly attributed believe(d) that questioning the foundations of quantum mechanics is(was) ultimately a waste of time. And at least one other person well known for spreading this meme is considered pretty pie in the sky.

It's a good essay and you present reasonable arguments. Hope is intrinsic to human nature. We feed from it. You should always give people a future and a perspective otherwise you lead them to depression. We don't like circles and dead ends. What we like is straight lines to infinity. Time for ever, progress for ever and boundless worlds. Limits and impossibilities imprison human mind and are unacceptable; we don't want to hear about them.

I wouldn't call it pessimism. If you tell yourself and your students that the theory you currently have doesn't have to be questioned since it's just the way Nature is, and you have nothing more to ask, it's a way to silence worries and justify lack of progress, not pessimism. It is also a way to focus attention on the "real" task, namely to work within the framework you've just stated shouldn't be questioned.

If I recall correctly, both Lee and Howard in their books wrote about how questions about the foundations of qm were addressed at physics department. Or rather not addressed. It is quite remarkable how similar their experiences are, despite that having been different decades in different country. An my experience has been exactly the same, another decade, another country. That's what my sentence referred to. To set the historical context you might find it interesting to watch the recording of David Kaiser's talk http://pirsa.org/08090034/, I think he talked about how that attitude spread.

The pie used the phrase in a different context. I was about to comment on that in the essay, but it would have lead to far off-topic. It isn't a good example for doubt anyway, because there's very few people who believe his argument. Best,

"What is ultimately possible in physics? I will argue here that it is ultimately impossible to answer this question."

I agree. It's clear that the FQXi essay topics are encouraging mindless speculation, like fortune telling, horoscopes of science, sci fi (or religious descriptions of the "world to come"), which have zero connection to solid science.

However, speculation is always more popular than science, which is why people like Kepler made their living doing astrology like horoscopes, and investigated the facts of nature as a hobby.

A very nice essay and as per usual one that forces me to ponder it for a while before even able to attempt making sensible comment. Something you might find as a point of interest, is that one of your other loyal, yet unlike myself, seldom heard from blog followers has also posted a submission to the FQXi essay contest; one which I share some affinity for his research direction, yet also thanks to you, we are both able to honestly boast having been mugged by a theoretical physicist:-)

With all this taken into consideration and if this time I could act as being Santa I would have you both awarded a prize.

An essay topic on important scientific facts currently censored out for crackpot reasons. Not speculations.

Aristarchus's discovery of the solar system was censored out because it was wrong in technical details (it used circular orbits) and the wrong mainstream model was better developed. Copernicus made it more predictive by adding epicycles, but it was a mess until Kepler discovered that elliptical orbits were best. Similarly, Larmarke's evolution was ignored and debunked because it made errors. This didn't stop Darwin from correcting the errors.

Sometimes therefore, central ideas that "everyone" agrees are rubbish turn out to be "right" (i.e. the simplest known theory to reproduce and predict the most observables) once the errors in them have been straightened out. Bigotry, of course, means that people spot an error then use that as an excuse to ignore the theory, instead of correcting the error!

Essays about such wrongly censored ideas is the kind of thing that might help make people think more scientifically and less stupidly.

I hope your essay wins, but instead I suspect the winner will be something stupid about the "physics" of reverse time-travel through wormholes following spin-2 gravitons in a supersymmetric 11-d braneworld.

If the sensitivity of a graviton detector must be attenuated to the degree that neutrino backgrounds swamp the signal, or else it collapses into a black hole, I'd say that's a pretty darn good example of a practical limitation to exploration. I greatly appreciate such helpful reminders. I also am in complete agreement that philosophical speculation about limits that are not firmly grounded in well-established physical principles only heaps speculation upon speculation, and is ultimately a big waste of time.

With a few notable exceptions (including your essay), I've failed to read much that is illuminating among the submissions, and a handful apparently aren't even about physics in any conventional sense. You could have just published your essay as a stand-alone blog post, and I doubt the world would have been any worse off for your choice of forum. What does FXQi hope to achieve with this, other than encouraging the god squad to chime in and muddy the waters with theological and philosophical distractions?

Anyway, in my (certainly disputable) knowledge of English this essay appears poorly defined, because the question "What is ultimately possible in physics?" can be understood like question for both nearest, both farthest point of human imagination.

Physics is limited by management for both discovery and abandonment. A grant funding proposal is an environmental impact report, an IPO, a sworn affidavit, and an enema. Young faculty are nekulturny; yobbo, chav, bogan, nong, ocker, naco...

Sorry, I don't quite get what you mean. What "facts" are allegedly "censored out" by whom? There is certainly (in all fields of science) experimental evidence that doesn't receive a lot of attention. Typically that's because there's trouble reproducing the experiment and/or debate about the methodology used in the experiment. Sometimes it turns out later that this skepticism was a mistake. That doesn't mean however the skepticism wasn't justified.

I don't know a single example of a "central idea that everyone agrees on is rubbish." I would be very surprised if you'd find any idea that everyone agrees on, period. But maybe we're not using the word "idea" in the same way.

I agree with you though that there is a tendency to ignore other people's work instead of arguing about its correctness. That is a very bad trend. It isn't hard to see though what it's caused by. There are no incentives for scientists to put forward criticism. It doesn't earn you credits, it just lets you come off as negative, and unfortunately a lot of people take criticism very personal. In addition, such ignorance is also often presented as openmindedness. The amount of controversy is to some extend cultural though. Americans for example suffer from an over-extreme politeness that sometimes isn't beneficial for scientific arguments. Mix them with some South or East Europeans and you get action.

Anyway, maybe one could slightly rephrase your suggestion as "What's the most underappreciated idea in contemporary physics?" Unfortunately, I am afraid that 99% of contributions would just advertise the author's own work, so it's probably not going to be very insightful. Best,

If we allow that any theoretical construct ultimately requires observational, BUT TENTATIVE evidence WITH ONLY FINITE CONFIDENCE in its support to move it into the realm of science, from the realm which is indistinguishable from either pure mathematics or ‘science fiction’ (as you essentially do at the bottom of page 5: “What we can thus state with certainty at any time is merely ‘To our best current knowledge...’ ”) then clearly, the only answer to the question: “What is ultimately possible in physics?” MUST BE“it is ultimately impossible to answer this question”.

Yeah, that's basically the one-line summary. You can never tell if something is fundamentally impossible because you can never verify your theories. The one catch being what I said at the end, if you stop thinking about it, progress becomes impossible indeed. Best,

Yes, I could just have posted it here on this blog. However, I thought via FQXi I might reach some people I usually don't reach. And they inspired me to think about the question in the first place, so I think it's appropriate. I suppose some of the reasons for the essay contest are community building, outreach, and initiating discussions. Best,

MgB2 is a BCS supercon with an "impossibly" high Tc = 39 kelvin. Multicomponent inorganic combinatorial studies had an undergrad doing the dreary setups. She insubordinately did binary component controls.

Uncle Al was tasked with isolating kerogen from oil shale (3-D crosslinked like epoxy). The literature is crap. Uncle Al dissolved the rock instead (HCl for carbonates then NH4HF2 for silicates) and caught Hell. The project as stated was to isolate kerogen from rock, not to remove rock and leave kerogen. Idiots.

Zephir: I hate to destroy your illusions about being the sole defender or the aether, but there are actually several established physicists who work on some sort of aether in one way or the other, Ted Jacobson being one of them. Best,

Competetion in contemporary science leads to emergent censorship. This censorship isn't organized, but the more uncompromising. This is why you're trying to separate my posts from discussion under various less or more transparent excuses.

/*..Ted Jacobson being one of them..*/Every theory is defined by its postulate set. Ted Jacobson models have nothing to do with Descartes aether model, because it doesn't uses it in his derivations, thus violating scientific priority and consistency of this concept. It's just another attempt of formally thinking theorists, how to make Aether concept vague and void in the eyes of society.

Aether is NOT some abstract vector field or quantum field or whatever else, but material particle gas.

Your negativism and personal problems with "chronically off-topic self-advertisements" are based on your fear of competition - despite of you're able/willing to admit it - or not. I'm not advertising yourself, remaining completely anonymous, I'm not filling blogs with stories from my personal life - but I'm explaining the relevance of ancient Aether concept.

Zephir: Look, no matter what topic I write on, you clog my comment section with "aether, aether, aether." I have already told you several times that I'm not interested in you theory of whatever and I regard your behavior as a crudely impolite abuse of our hospitality. You prefer to call that "censorship" simply because it makes you feel more relevant. I don't quite notice any "competition" that I could be afraid of.

You can explain the relevance of the aether concept all you like, but not if that's not the topic we are discussing. I hope that was clear. You have pretty much exhausted my patience. Best,

/*...and undergrads who disobey orders (MgB2 supercon Tc)....*/MgB2 superconductor isn't so fundamental at all - just try to search for Prins and superconductivity keywords on the web. Room temperature superconductivity was revealed by guy, which even didn't interested about superconductivity at all.

Despite your pleading for common sense, decency, decorum and other words that would serve to describe thoughtful and civilized conduct, all has had no effect. This I would accredit to being only assignable to someone not having the capacity to understand such concepts, since they have to do with requiring having at least some minimal ability to extending ones sense of being beyond simply themselves. I would therefore suggest then there is only one often used request made in such circumstance and that’s ask of them “ Not that I would wish you to go away angry, yet never the less please go away” :-)

Best,

Phil

Sorry I made an error in my first attempt to make comment and wish I could say it attributable to the frustration such aforementioned people invoke, yet that as you know wouldn't serve as being either a reasonable or honest explanation :-)

Another thought has just come to mind in regards to what I said earlier. I’m reminded that you have always had a policy regarding this blog from the outset that you would not accept, unlike some others have, paid advertisements. This I’ve always thought to be a sound, thoughtful and ethical decision on your part. However, in this case you should consider making an exception and accept Zephir as being one. You could put his comments in a special side bar with a link to his website. This way on one hand would leave you having to put up with some annoyance, on the other you would be compensated in some respect. However, I wouldn’t recommend a ‘pay per click’ arrangement, as that I fear would not gather you enough to justify what’s would be required.

Also, it would be interesting to discover if our friend is confident and committed enough to his ideas to put his money where his mouth is; as they say :-)

a quite objective sign of long-term censorship and conformism of every blog is an occurrence of very loyal, i.e. devote if not sectarian readers, who are result as an long-term selection and evolutionary adaptation (simillia simillibus attractur - compare the Motl's blog for some nice asocial demo).

As a censorship should be considered a dishonesting of commenters and every action, undeniable purpose of which is to make further commenting less pleasant for certain group of readers (you can read a bit about emergent strategies here and on my blog, too).

Zephir: If you meant to say that this blog gathers reasonable and polite people interested in constructive exchange and you don't fit in, that's correct. If you think I'm making it unpleasant for you to spam my comment section with your self-advertisements I'm not interested in and that make no useful contribution, that was exactly my intention. I think we are making progress here.

The only step missing is that you conclude instead of repeating your ridiculous complaints about "censorship" because I want to keep discussions on topic you should either make contributions to the topic, or - since I have the impression you're not interested in what we talk about anyway - go elsewhere. Best,

"The amount of controversy is to some extend cultural though. Americans for example suffer from an over-extreme politeness that sometimes isn't beneficial for scientific arguments. Mix them with some South or East Europeans and you get action. "

Yes, the kind of action one gets from Lubos Motl.

I'm sorry, but the very strong impression I have of "criticism" at conferences is that it always *is* personal. Invariably the person doing the criticising has a history of conflict either with the person speaking or with the research programme he or she represents, and the "criticism" is a very badly disguised way of belittling either the speaker or what he or she represents. And indeed the East Europeans are the worst in this respect. It can be entertaining but it is never enlightening. As somebody said to me at a conference where that happened, "Conferences are an extension of war by other means."

Please. Virtually all papers are forgotten within a year or less, whether they are right or wrong. There is no need to talk about bad papers except in those cases where they trigger off an avalanche of other bad papers. By all means excoriate Howard Georgi for that silly unparticle nonsense, but it's best to leave those unfortunate people who wrote papers citing him to their fate.

“Scientific progress is driven by curiosity, and the desire to contribute a piece to mankind’s increasing body of knowledge. It lives from creativity, from stubbornness, and from hope. What I have shown here is that there is always reasonto hope.” -Sabine Hossenfelder-The Frontier of Knowledge

I find your summation to be the most compelling part of your argument as to why physicists have reason to understand we have not hit the wall with what we can discover about the nature of the world. That is to say, what ultimately could restrict creatures that represent being the manifestation of the conscious nature of the universe, whether they are unique to only this world or part of any that is possible; for in the end we have demonstrated as able to contemplate all of it. I've always found this to have been best expressed by the late Carl Sagan when he argued the same as follows:

“For we are the local embodiment of a Cosmos grown to self-awareness. We have begun to contemplate our origins; starstuff pondering the stars; organizing assemblages of ten billion billion billion atoms considering the evolution of atoms; tracing the long journey by which, here at least, consciousness arose. Our loyalties are to the species and the planet. We speak for earth. Our obligation to survive is owed not just to ourselves but also to that Cosmos, ancient and vast, from which we sprang.” -Carl Sagan-Cosmos

"Sorry, I don't quite get what you mean. What "facts" are allegedly "censored out" by whom? ... I am afraid that 99% of contributions would just advertise the author's own work, so it's probably not going to be very insightful."

Hi Bee,

The facts concerning the exact areas where the Standard Model and General Relativity are scientific facts and the areas where they are untested epicycle-type speculations are currently censored out by everyone as far as I can tell. Can anybody name just one book or article which distinguishes the facts of the Standard Model or General relativity from the speculations? No. Nobody wants to be scientific.

In each case, instead of keeping to facts about the theory, people say that the Higgs mechanism and the electroweak unification at high energy (neither of which is empirically verified) in the Standard Model is true because the theory makes correct predictions in other areas. Likewise, instead of recognising that general relativity is just a classical field model of gravity with a landscape of many possible cosmologies, it is universally presented as completely verified.

Instead of being specific about what is fact and what is so far just speculation (untested hypothesis), the mainstream tries to turn it all into a dogmatic religion:

"You're either with us, or against us" - Jesus (Matthew 12:30 and Mark 9:40).

Science, by contrast to this dogmatic groupthink religion, is the opposite:

"Science is the organized skepticism in the reliability of expert opinion." - R. P. Feynman (quoted by Smolin, The Trouble with Physics, 2006, p. 307).

I can't understand why you think that the author of a new piece of work is the wrong person to explain it. Surely, that is the best person to explain it, having developed it? Just goes to prove how stupid I am

(Some books like Feynman's "QED" and Peter Woit's "Not Even Wrong" list and discuss some of the issues with the Standard Model, like those in the Higgs field and the empirically-fitted Weinberg electroweak mixing angle, but even the best of them don't make the point that parts of them theory are tested facts and other parts are just epicycles. E.g., Feynman writes at one place in "QED" that the Weinberg mixing angle in electroweak unification is just duct tape, but he then smoothes things over and obfuscates!)

Well, that comment was meant tongue in cheek, sorry if that wasn't clear. I've seen my share of pointless fights and know what you're talking about. I am sorry to hear though that the criticism you have witnessed has always been of the personal sort. While I have certainly seen that too, I have luckily also seen and experienced the other side, that of constructive non-personal criticism. It has for me repeatedly been very useful, and I appreciate that very much. Otoh, I don't take criticism on my research personally myself, maybe that plays a role. Best,

No clue what books you've read/lectures you've heard. The ones I have tell you what the theory is, what the tests are, to what precision it has been tested, and ideally also cover possible extensions/alternatives and constraints on these, though you might have to refer to a review article for the latter in case your book isn't up to date (which textbooks frequently are). My favorite GR book is Sexl and Urbantke's, though it's in German (there might be an English version, but it doesn't seem to be very widely used overseas). Reg QFT, I find very recommendable Halzen and Martin, together with Peskin and Schroeder, and Weinberg's trilogy as good measure. I also like Weinberg's book on Graviation and Cosmology, but it's quite outdated.

But I think you seem to have an issue not with GR and QFT, but instead with physics beyond the standard model, in particular unification and possibly quantum gravity, which is so far untested (it's somewhat a matter of terminology, some people claim neutrino oscillations is physics beyond the sm already). It is indeed sad but true (I have commented on that several times elsewhere), that many people working on these speculations do frequently feeel the need to inappropriately advertise their work by focusing on the pros and neglecting the cons. (Typically justified by saying everybody knows the cons anyway.) It is this behavior that Peter tried to address in his book. You have to keep in mind however that the facts are not hidden. They just aren't as objectively pointed out as should be. You probably know that I have my theory of the dynamics of the academic system that causes that, this was in fact content of the talk I gave on the Atlanta Conference, but I don't want to go into this now.

I didn't say that the author of a new piece of work is the wrong person to explain it. I said that this isn't what I'd consider an interesting essay contest. If you want to read people's explanations of their own work, just go and check the arxiv.